The present invention relates to the use of branched polyesters obtainable by polycondensation of citric acid with at least one polyalcohol, and optionally with polycarboxylic acid component as additive in washing compositions, cleaners, detergents or a formulation for water treatment and to mixtures comprising such branched polyesters. The invention further relates to the use of hydrophobically modified branched polyesters, and to the method for cleaning, washing or water treatment using such branched polyesters.
WO 93/22362 describes a process for preparing polyesters from citric acid and polyhydroxyl compounds and their use as additive to low-phosphate or phosphate-free detergents and cleaners. The polyhydroxyl compounds are oligo- and polysaccharides, modified oligo- and polysaccharides, and polyvinyl alcohols.
U.S. Pat. No. 5,652,330 describes polycondensates of citric acid which are either polycondensates of citric acid with itself or into which alcohol components are condensed in deficiency with a molar ratio of 100:1 to 2.5:1. The polycondensates described therein are used in detergents and cleaners especially for preventing scale deposits.
WO 2012/028496 describes branched polyesters which comprise citric acid as structural component, processes for preparing such polyesters, and their use for solubilizing sparingly soluble, basic pharmaceutical active ingredients.
WO 92/16493 claims citric acid esters of polyhydroxyl compounds such as polyglycerol or sugar alcohols and their use in detergents and cleaners.
Polymers obtainable by free-radical polymerization and composed of carboxyl-group-containing and/or sulfonic acid-group-containing monomers have been an important constituent of phosphate-containing and phosphate-free machine dishwashing detergents for many years. By virtue of their soil-dispersing and deposit-inhibiting effect, they make a considerable contribution to the cleaning and rinsing performance of machine dishwashing compositions. For instance, they ensure that no salt deposits of the hardness-forming calcium and magnesium ions remain on the ware.
Homopolymers of acrylic acid or copolymers of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are often used for this purpose.
These polymers are also used in water-conveying systems as agents for preventing mineral deposits such as e.g. calcium and magnesium sulfate, magnesium hydroxide, calcium and barium sulfate and calcium phosphate on heat transfer surfaces or in pipelines. Water-conveying systems to be mentioned here are inter alia cooling and boiler feed water systems and industrial process waters. However, these polymers are also used as scale inhibitors in the desalination of seawater or brackish water by distillation and by membrane processes such as reverse osmosis or electrodialysis.
One disadvantage of these polymers obtainable by free-radical polymerization and composed of carboxyl-group-containing and/or sulfonic acid-group-containing monomers is that they are not biodegradable. Biodegradable polymers such as, for example, polyaspartic acid, however, have struggled to gain acceptance commercially due to the high production costs.